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Michael Ocampo via Flickr Creative Commons // CC BY 2.0
Michael Ocampo via Flickr Creative Commons // CC BY 2.0

How Tomatoes Fend Off Parasitic Vines

Michael Ocampo via Flickr Creative Commons // CC BY 2.0
Michael Ocampo via Flickr Creative Commons // CC BY 2.0

When medieval guards spotted invaders in the distance, they’d pull up the drawbridge and fortify their castle’s defenses. A horse that senses biting flies will flick its tail. The whine of a mosquito’s wings is our cue to start swatting. Plants under attack can’t do any of these things, but that doesn’t mean they’re helpless. Researchers say some tomato plants can sense and defend themselves against encroaching parasitic vines. They published their findings this week in the journal Science. 

Plants’ ability to converts sunlight into nutrients, combined with their inability to run away, makes them juicy targets for bugs, microbes, fungi, and parasitic vines. Experts estimate that parasitic plants alone cause billions of dollars of agricultural damage every year [PDF].

But plants aren’t going down without a fight. Many species have evolved physical defenses like thorns, while others turn to chemical warfare, pumping out terrible-tasting or toxic compounds as soon as they sense a threat. They’re vigilant monitors of chemical signals in their environments, and can even identify invading microbes by their molecules. One plant even farts in the face of danger.

Researchers wondered if the molecular ID technique could work against other types of parasites as well. They decided to test the concept on the tomato plant (Solanum lycopersicum) and one of its would-be adversaries, a vine called Cuscuta reflexa. We say "would-be" because, unlike many of its relatives, S. lycopersicum has somehow found a way to fend off the mooching vine.

C. reflexa on the susceptible tomato relative S. pennellii. Image credit: Eric Melzer

The key moment in host/parasite combat for C. reflexa happens when the vine is still young. Although its seeds are quite hardy, germinating C. reflexa seedlings are vulnerable and will die unless they can find and successfully colonize a plant host within a few days. That colonization can only happen if the parasite can quickly produce syringe-like feeding structures called haustoria that pierce the plant’s cell wall and suck out the nutrients within. To thwart the vine, then, a potential host has to stop the haustoria before they start. And to do that, it needs to know the parasite is there. 

To test the tomato plant's ability to sense its presence, the researchers clipped off small samples of its leaves and dropped them into beakers, to which they also added purified extracts of C. reflexa molecules. They also set up control beakers containing the C. reflexa essence and samples of other, more susceptible plants. Experimenters then took samples of the air inside the beakers and tested it to find out if the alarmed plants were releasing defensive chemicals. 

Sure enough, S. lycopersicum sensed the parasitic vine’s molecules and went into defensive mode. The other plants just kind of … sat there.

Molecular analysis of all the host plants revealed that S. lycopersicum alone contains a receptor protein that the researchers called CUSCUTA RECEPTOR 1, or CuRe1. 

Biologists Vardis Ntoukakis of the University of Warwick and Selena Gimenez-Ibanez of Spain’s Centro Nacional de Biotecnología were not involved in the research, but praised the team’s results. “The identification of CuRe1 represents a major breakthrough in understanding the strategies used by plants to sense danger from diverse origins,” they wrote in a commentary in Science.

They note that other types of parasites also rely on haustoria, and say it makes sense that hosts would use the same mechanisms to keep them all out.

“This work greatly advances our understanding of the mechanisms controlling plant resistance to parasitic plants while at the same time opening up new avenues of research.”

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15 Confusing Plant and Animal Misnomers
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iStock

People have always given names to the plants and animals around us. But as our study of the natural world has developed, we've realized that many of these names are wildly inaccurate. In fact, they often have less to say about nature than about the people who did the naming. Here’s a batch of these befuddling names.

1. COMMON NIGHTHAWK

There are two problems with this bird’s name. First, the common nighthawk doesn’t fly at night—it’s active at dawn and dusk. Second, it’s not a hawk. Native to North and South America, it belongs to a group of birds with an even stranger name: Goatsuckers. People used to think that these birds flew into barns at night and drank from the teats of goats. (In fact, they eat insects.)

2. IRISH MOSS

It’s not a moss—it’s a red alga that lives along the rocky shores of the northern Atlantic Ocean. Irish moss and other red algae give us carrageenan, a cheap food thickener that you may have eaten in gummy candies, soy milk, ice cream, veggie hot dogs, and more.

3. FISHER-CAT

Native to North America, the fisher-cat isn’t a cat at all: It’s a cousin of the weasel. It also doesn’t fish. Nobody’s sure where the fisher cat’s name came from. One possibility is that early naturalists confused it with the sea mink, a similar-looking creature that was an expert fisher. But the fisher-cat prefers to eat land animals. In fact, it’s one of the few creatures that can tackle a porcupine.

4. AMERICAN BLUE-EYED GRASS

American blue-eyed grass doesn’t have eyes (which is good, because that would be super creepy). Its blue “eyes” are flowers that peek up at you from a meadow. It’s also not a grass—it’s a member of the iris family.

5. MUDPUPPY

The mudpuppy isn’t a cute, fluffy puppy that scampered into some mud. It’s a big, mucus-covered salamander that spends all of its life underwater. (It’s still adorable, though.) The mudpuppy isn’t the only aquatic salamander with a weird name—there are many more, including the greater siren, the Alabama waterdog, and the world’s most metal amphibian, the hellbender.

6. WINGED DRAGONFISH

This weird creature has other fantastic and inaccurate names: brick seamoth, long-tailed dragonfish, and more. It’s really just a cool-looking fish. Found in the waters off of Asia, it has wing-like fins, and spends its time on the muddy seafloor.

7. NAVAL SHIPWORM

The naval shipworm is not a worm. It’s something much, much weirder: a kind of clam with a long, wormlike body that doesn’t fit in its tiny shell. It uses this modified shell to dig into wood, which it eats. The naval shipworm, and other shipworms, burrow through all sorts of submerged wood—including wooden ships.

8. WHIP SPIDERS

These leggy creatures are not spiders; they’re in a separate scientific family. They also don’t whip anything. Whip spiders have two long legs that look whip-like, but that are used as sense organs—sort of like an insect’s antennae. Despite their intimidating appearance, whip spiders are harmless to humans.

9. VELVET ANTS

A photograph of a velvet ant
Craig Pemberton, Wikimedia Commons // CC BY-SA 3.0

There are thousands of species of velvet ants … and all are wasps, not ants. These insects have a fuzzy, velvety look. Don’t pat them, though—velvet ants aren’t aggressive, but the females pack a powerful sting.

10. SLOW WORM

The slow worm is not a worm. It’s a legless reptile that lives in parts of Europe and Asia. Though it looks like a snake, it became legless through a totally separate evolutionary path from the one snakes took. It has many traits in common with lizards, such as eyelids and external ear holes.

11. TRAVELER'S PALM

This beautiful tree from Madagascar has been planted in tropical gardens all around the world. It’s not actually a palm, but belongs to a family that includes the bird of paradise flower. In its native home, the traveler’s palm reproduces with the help of lemurs that guzzle its nectar and spread pollen from tree to tree.

12. VAMPIRE SQUID

Drawing of a vampire squid
Carl Chun, Wikimedia Commons // Public Domain

This deep-sea critter isn’t a squid. It’s the only surviving member of a scientific order that has characteristics of both octopuses and squids. And don’t let the word “vampire” scare you; it only eats bits of falling marine debris (dead stuff, poop, and so on), and it’s only about 11 inches long.

13. MALE FERN & LADY FERN

Early botanists thought that these two ferns belonged to the same species. They figured that the male fern was the male of the species because of its coarse appearance. The lady fern, on the other hand, has lacy fronds and seemed more ladylike. Gender stereotypes aside, male and lady Ferns belong to entirely separate species, and almost all ferns can make both male and female reproductive cells. If ferns start looking manly or womanly to you, maybe you should take a break from botany.

14. TENNESSEE WARBLER

You will never find a single Tennessee warbler nest in Tennessee. This bird breeds mostly in Canada, and spends the winter in Mexico and more southern places. But early ornithologist Alexander Wilson shot one in 1811 in Tennessee during its migration, and the name stuck.

15. CANADA THISTLE

Though it’s found across much of Canada, this spiky plant comes from Europe and Asia. Early European settlers brought Canada thistle seeds to the New World, possibly as accidental hitchhikers in grain shipments. A tough weed, the plant soon spread across the continent, taking root in fields and pushing aside crops. So why does it have this inaccurate name? Americans may have been looking for someone to blame for this plant—so they blamed Canada.

A version of this story originally ran in 2015.

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Watch an Antarctic Minke Whale Feed in a First-of-Its-Kind Video
WWF
WWF

New research from the World Wildlife Fund is giving us a rare glimpse into the world of the mysterious minke whale. The WWF worked with Australian Antarctic researchers to tag minke whales with cameras for the first time, watching where and how the animals feed.

The camera attaches to the whale's body with suction cups. In the case of the video below, the camera accidentally slid down the side of the minke whale's body, providing an unexpected look at the way its throat moves as it feeds.

Minke whales are one of the smallest baleen whales, but they're still pretty substantial animals, growing 30 to 35 feet long and weighing up to 20,000 pounds. Unlike other baleen whales, though, they're small enough to maneuver in tight spaces like within sea ice, a helpful adaptation for living in Antarctic waters. They feed by lunging through the sea, gulping huge amounts of water along with krill and small fish, and then filtering the mix through their baleen.

The WWF video shows just how quickly the minke can process this treat-laden water. The whale could lunge, process, and lunge again every 10 seconds. "He was like a Pac-Man continuously feeding," Ari Friedlaender, the lead scientist on the project, described in a press statement.

The video research, conducted under the International Whaling Commission's Southern Ocean Research Partnership, is part of WWF's efforts to protect critical feeding areas for whales in the region.

If that's not enough whale for you, you can also watch the full 13-minute research video below:

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